[iso_extract tests] Fix another bad EPEL hardcode

Change:
- Use mirrorlist instead of baseurl here.

Test Plan:
- ci_complete

Signed-off-by: Rick Elrod <rick@elrod.me>

test/integration/targets/iso_extract/tasks/7zip.yml

@@ -25,7 +25,7 @@
   yum_repository:
     name: epel
     description: EPEL yum repo
-    baseurl: https://download.fedoraproject.org/pub/epel/{{ ansible_distribution_major_version }}/{{ ansible_architecture }}/
+    mirrorlist: https://mirrors.fedoraproject.org/metalink?repo=epel-{{ ansible_distribution_major_version }}&arch=$basearch
     state: present
   when: ansible_distribution in ['CentOS']